Any idea why this happens to you? Your story suggests some targeting.
This was back in the 1990s, when asking for your password wasn't a thing I've ever heard of them doing, but also when me bringing 128-bit encryption software (aka the US version of Netscape Navigator) to Japan, where I was a foreign student, was a serious crime akin to arms smuggling.
Of course, I never found out for sure why I was on that list, and eventually I apparently wasn't on it anymore. But during that time I did read a fascinating article in some magazine, by Nathan Myhrvold (the now-infamous patent troll scumbag). Apparently, he was on the same list, despite being a super rich fat white guy from Microsoft.
His theory was that he got on the list by buying one-way plane tickets in cash. That resonated with me, because I often did the same thing back then… I just never really knew when I wanted to come back, and I didn't have much credit on my one credit card.
That's obviously both circumstantial and anecdotal, however I don't think it really takes too much to get on one of these secret (and very probably unlawful, but effectively un-challengeable) lists.
What could the "fat" part of that possibly have to do with anything related to targeting, other than as a cheap excuse for you to denigrate Myhrvold?
But also, yeah: fuck Nathan Myhrvold. He's a smarmy piece of shit whose parasitical exploitation of America's societal weaknesses and dysfunction far outweighs all the modest contributions he's ever made. I hope he trips and falls face-first into one of his large sous-vide contraptions.
(That time, I was denigrating him on purpose.)
NSA didn't want to allow Microsoft to build RSA into Windows and export it. Even though the cat was out of the bag and foreign OEMs and vendors were already selling RSA. NSA wanted Microsoft to not give users more than 40 bits of encryption keys.
So Myhrvold, as President of Microsoft, flippantly offered to pad the keys generated by Windows with NSA's public RSA key. Win Win. Users can export more than 40 bits, and NSA gets a backdoor.
Microsoft won and was allowed to export software using RSA. No doubt that little stunt put Myhrvold on some Watchlist for Life.
It's too bad he became evil after he became a billionaire and started only caring about money and Yachts and hob knobbing with other 1% elites.
Border guards have the power to prevent you from entering the country if they believe your business is unlawful, and asking those questions is one of the ways they decide. We can question whether border guards ought to exist, but, given that they do, refusing to answer their questions seems like a ticket to a back room for hours.
You really never answered their questions on every entry?
If exercising my human rights is "a ticket to a back room for hours", then something is fundamentally broken in our society. You should try it; without doing so you actually have no data about the practical perimeter of your basic rights. This stuff isn't printed in the newspaper.
Yes, I really never answered their questions, except the ones about citizenship and nationality and place of birth—which I answered by presenting my passport.
"Business or pleasure?" is a vague, leading question designed to get you to volunteer as much information as possible. Sometimes I replied "no" or "yes" to that one, with an occasional "On advice of my attorney I decline to answer questions from police except in writing and via counsel" thrown in to break up the monotony.
Never talk to the police.
No. The USA can never deny entry to citizens (nor any other country). They may arrest you on the spot, but can't deny you entry.
Green card holders is a different story, they have no right to enter and are at the discretion of the authorities.